AQA A Level Biology

Revision Notes

1.6.1 The Structure of ATP

The Structure of ATP

  • All organisms require a constant supply of energy to maintain their cells and stay alive
  • This energy is required:
    • In anabolic reactions – building larger molecules from smaller molecules
    • To move substances across the cell membrane (active transport) or to move substances within the cell
    • In animals, energy is required:
      • For muscle contraction – to coordinate movement at the whole-organism level
      • In the conduction of nerve impulses, as well as many other cellular processes
  • In all known forms of life, ATP from respiration is used to transfer energy in all energy-requiring processes in cells
  • This is why ATP is known as the universal energy currency
  • Adenosine Triphosphate (ATP) is a nucleotide
    • The monomers of DNA and RNA are also nucleotide


  • Adenosine triphosphate (ATP) is the energy-carrying molecule that provides the energy to drive many processes inside living cells
  • ATP is another type of nucleic acid and hence it is structurally very similar to the nucleotides that make up DNA and RNA
  • It is a phosphorylated nucleotide
  • Adenosine (a nucleoside) can be combined with one, two or three phosphate groups
    • One phosphate group = adenosine monophosphate (AMP)
    • Two phosphate groups = adenosine diphosphate (ADP)
    • Three phosphate groups = adenosine triphosphate (ATP)

Structure of ATP, downloadable AS & A Level Biology revision notes

The structure of AMP, ADP and ATP

Exam Tip

Don’t worry – you are not expected to know the structural formulae for the nucleotides that make up AMP, ADP and ATP (as in the diagram above)! You just need to learn the different groups that they are made up of ( pentose sugars and nitrogenous bases and how many phosphate groups,).

Remember that adenine is a nitrogenous base whereas adenosine is a nucleoside (a base – adenine, attached to a pentose sugar).

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